2-Iminopiperidine hydrochloride

Selective inhibitors of neuronal nitric oxide synthase--is no NOS really good NOS for the nervous system?[Pubmed:9226999]

Trends Pharmacol Sci. 1997 Jun;18(6):204-11.

It is now ten years since NO was shown to account for the biological activity of endothelium-derived relaxing factor (EDRF). It is also the tenth anniversary of the identification of L-NG monomethyl arginine (L-NMMA) as the very first inhibitor of NO biosynthesis. That EDRF and NO were one and the same sparked an explosion of interest in the biochemistry and pharmacology of NO which has yet to subside. In contrast, the first ever nitric oxide synthase (NOS) inhibitor slipped seamlessly into the literature virtually without comment at the time. Over the following decade, L-NMMA (and like NOS inhibitors) have proved invaluable as tools for probing the biological roles of NO in health and disease and, in particular, have increased our understanding of the function of NO in the nervous system. Further advances in this important area now require the development of inhibitors selective for the neuronal isoform of NOS (nNOS). Here, Philip Moore and Rachel Handy provide an up-to-date account of the literature regarding the biochemical and pharmacological characterization of NOS inhibitors with particular reference to compounds with greater selectivity for the nNOS isoform.

2-Iminopiperidine and other 2-iminoazaheterocycles as potent inhibitors of human nitric oxide synthase isoforms.[Pubmed:8576908]

J Med Chem. 1996 Feb 2;39(3):669-72.

A series of 2-iminoazaheterocycles have been prepared and shown to be potent inhibitors of human nitric oxide synthase (NOS) isoforms. This series includes cyclic amidines ranging from five- to nine-membered rings, of which 2-iminopiperidine and 2-iminohomopiperidine were the most potent inhibitors, with IC50 values of 1.0 and 2.0 microM, respectively, for human inducible nitric oxide synthase. This series of cyclic inhibitors was further expanded to include analogs with heteroatoms in the 3-position of the six-membered ring. This modification was tolerated for sulfur and oxygen, but nitrogen reduced the inhibitory potency. The oral administration of 2-iminopiperidine in lipopolysaccharide (LPS)-treated rats inhibited the LPS-induced increase in plasma nitrite/nitrate levels in a dose-dependent manner, demonstrating its ability to inhibit inducible NOS activity in vivo. These cyclic amidines represent a new class of potent NOS inhibitors and the foundation for potential therapeutic agents.

Amidines are potent inhibitors of nitric oxide synthases: preferential inhibition of the inducible isoform.[Pubmed:8719415]

Eur J Pharmacol. 1995 Nov 30;291(3):311-8.

We evaluated the ability of simple alkyl amidines to inhibit the activity of the inducible isoform of nitric oxide (NO) synthase in vitro. In immunostimulated J774 macrophages, 2-iminopiperidine (EC50 = 10 microM) and butyramidine (EC50 = 60 microM) were more potent than NG-methyl-L-arginine (EC50 = 70 microM) in inhibiting nitrite formation. The five amidines tested for their ability to inhibit the conversion of L-arginine to L-citrulline by bovine endothelial cell homogenates (a source of the constitutive, endothelial NO synthase isoform) were less effective than NG-nitro-L-arginine or NG-methyl-L-arginine. The rank-order of the potencies of the amidines against the endothelial NO synthase was, in general, similar to the rank-order of the pressor effects of these agents in anesthetized rats. Thus, certain amidines are potent inhibitors of NO synthase, and are more selective towards the inducible NO synthase than the commonly used L-arginine based NO synthase inhibitors.